1. Field of the Invention
The present invention relates to an airbag system for protecting a vehicular occupant by softening shock of a vehicle collision with using an airbag inflated when the vehicle collision takes place.
2. Related Art
An Airbag system is already known as a vehicular occupant protective system to protect a vehicular occupant in case of a vehicle collision. The airbag system is composed of a sensor for detecting a vehicle collision, an inflator for erupting gas based on a signal from the sensor and an airbag that inflates with the gas erupted from the inflator, etc.
When a vehicle comes into collision, the airbag inflates with the gas between the vehicular occupant and interior components of the vehicle, such as a dashboard or a steering wheel located in front of the vehicular occupant. The inflated airbag softens shock to the vehicular occupant when the vehicular occupant collides with these interior components. For the vehicular occupant on a passenger seat, it is preferable to inflate the airbag directly towards the vehicular occupant to protect effectively, because at the passenger seat, a distance between the vehicular occupant and a position in which the airbag can be installed is greater than that at the driver seat. Thus, in the prior art, the airbag system is installed at the center of the dashboard facing the vehicular occupant of the passenger seat. This is so-called mid-mount form. Particularly, if the airbag which has a small air capacity is used to protect the vehicular occupant of the passenger seat, the mid-mount form is generally adopted.
However, even if the airbag system is sufficiently compact by using the airbag of the small air capacity, installing the airbag system at the center of the dashboard restricts flexibility of structures and shapes of other components to be installed inside the dashboard. In addition, the airbag may strike and damage the vehicular occupant's face because the airbag inflates directly towards the vehicular occupant's face. To solve such problems, installing an airbag system in an upper part of the dashboard is proposed. In this case, an inflator which erupts gas to an airbag is arranged in the upper part of the dashboard so that the airbag inflates along a windshield of the vehicle first, then a gap between the passenger and interior components such as the dashboard is filled with the inflated airbag.
However, the following problems arise if the airbag system is installed and operated as described above. For instance, in case of an airbag system having an airbag which is sewed two-dimensionally, the airbag is more likely to be hindered from inflating by the windshield. Moreover, interference between the airbag and the windshield obstructs inflation of the airbag, thus the gap between the vehicular occupant and interior components such as the dashboard cannot be sufficiently filled with the inflated airbag. As a result, it is difficult to sufficiently absorb the shock to the vehicular occupant at the vehicle collision.
Even if the airbag system can be installed in the upper part of the dashboard, to solve the above problems, an airbag disclosed in Japanese Patent Application Laid-Open No. Hei. 4-193645 can be employed. This airbag is formed by sewing s three pieces of cloths three-dimensionally in such a way that the airbag matches shapes of surrounding components like the windshield when the airbag inflates. This improves flexibility in selection of installation area for the airbag system.
However, employing a three-dimensionally sewed airbag to enable installation of the airbag system in the upper part of the dashboard, like the conventional system, will require additional processes in manufacture of airbags, thus resulting in increasing manufacturing costs.